The invention relates to an operating state circuit for an inverter and to a method for setting operating states of an inverter, in particular for an inverter for supplying power to a synchronous machine.
Electric drives of hybrid or electric vehicles can have permanent magnet electric machines, in particular synchronous machines, to which AC voltage is supplied by means of a pulse-controlled inverter. In this case, in the event of fault states on the low-voltage side, for example in the event of failure of the electronic driving, the power supply, various sensors, data communication or a fuse, it may be necessary to set a safe state in the inverter, i.e. a switching state of the inverter in which safety for people accessing the vehicle, such as rescue services in the event of an accident, and for the integrity of the electrical system is still ensured.
Document DE 10 2009 047 616 A1 discloses an inverter circuit for an electric machine which, in the event of a fault, can be transferred from the operating state of an active short circuit into the operating state of freewheeling.